using System;
namespace ch.ethz.ssh2.crypto.cipher
{
	
	/*
	This file is based on the 3DES implementation from the Bouncy Castle Crypto package.
	Their licence file states the following:
	
	Copyright (c) 2000 - 2004 The Legion Of The Bouncy Castle
	(http://www.bouncycastle.org)
	
	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:
	
	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.
	
	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE. 
	*/
	
	/// <summary> DES.
	/// 
	/// </summary>
	/// <author>  See comments in the source file
	/// </author>
	/// <version>  2.50, 03/15/10
	/// 
	/// </version>
	public class DES : BlockCipher
	{
		virtual public System.String AlgorithmName
		{
			get
			{
				return "DES";
			}
			
		}
		virtual public int BlockSize
		{
			get
			{
				return 8;
			}
			
		}
		private int[] workingKey = null;
		
		/// <summary> standard constructor.</summary>
		public DES()
		{
		}
		
		/// <summary> initialise a DES cipher.
		/// 
		/// </summary>
		/// <param name="encrypting">whether or not we are for encryption.
		/// </param>
		/// <param name="key">the parameters required to set up the cipher.
		/// </param>
		/// <exception cref="IllegalArgumentException">if the params argument is inappropriate.
		/// </exception>
		public virtual void  init(bool encrypting, byte[] key)
		{
			this.workingKey = generateWorkingKey(encrypting, key, 0);
		}
		
		public virtual void  transformBlock(byte[] input, int inOff, byte[] output, int outOff)
		{
			if (workingKey == null)
			{
				throw new System.SystemException("DES engine not initialised!");
			}
			
			desFunc(workingKey, input, inOff, output, outOff);
		}
		
		public virtual void  reset()
		{
		}
		
		/// <summary> what follows is mainly taken from "Applied Cryptography", by Bruce
		/// Schneier, however it also bears great resemblance to Richard
		/// Outerbridge's D3DES...
		/// </summary>
		
		internal static short[] Df_Key = new short[]{(short) (0x01), (short) (0x23), (short) (0x45), (short) (0x67), (short) (0x89), (short) (0xab), (short) (0xcd), (short) (0xef), (short) (0xfe), (short) (0xdc), (short) (0xba), (short) (0x98), (short) (0x76), (short) (0x54), (short) (0x32), (short) (0x10), (short) (0x89), (short) (0xab), (short) (0xcd), (short) (0xef), (short) (0x01), (short) (0x23), (short) (0x45), (short) (0x67)};
		
		internal static short[] bytebit = new short[]{(short) (128), (short) (64), (short) (32), (short) (16), (short) (8), (short) (4), (short) (2), (short) (1)};
		
		internal static int[] bigbyte = new int[]{0x800000, 0x400000, 0x200000, 0x100000, 0x80000, 0x40000, 0x20000, 0x10000, 0x8000, 0x4000, 0x2000, 0x1000, 0x800, 0x400, 0x200, 0x100, 0x80, 0x40, 0x20, 0x10, 0x8, 0x4, 0x2, 0x1};
		
		/*
		* Use the key schedule specified in the Standard (ANSI X3.92-1981).
		*/
		
		internal static byte[] pc1 = new byte[]{56, 48, 40, 32, 24, 16, 8, 0, 57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 60, 52, 44, 36, 28, 20, 12, 4, 27, 19, 11, 3};
		
		internal static byte[] totrot = new byte[]{1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 23, 25, 27, 28};
		
		internal static byte[] pc2 = new byte[]{13, 16, 10, 23, 0, 4, 2, 27, 14, 5, 20, 9, 22, 18, 11, 3, 25, 7, 15, 6, 26, 19, 12, 1, 40, 51, 30, 36, 46, 54, 29, 39, 50, 44, 32, 47, 43, 48, 38, 55, 33, 52, 45, 41, 49, 35, 28, 31};
		
		internal static int[] SP1 = new int[]{0x01010400, 0x00000000, 0x00010000, 0x01010404, 0x01010004, 0x00010404, 0x00000004, 0x00010000, 0x00000400, 0x01010400, 0x01010404, 0x00000400, 0x01000404, 0x01010004, 0x01000000, 0x00000004, 0x00000404, 0x01000400, 0x01000400, 0x00010400, 0x00010400, 0x01010000, 0x01010000, 0x01000404, 0x00010004, 0x01000004, 0x01000004, 0x00010004, 0x00000000, 0x00000404, 0x00010404, 0x01000000, 0x00010000, 0x01010404, 0x00000004, 0x01010000, 0x01010400, 0x01000000, 0x01000000, 0x00000400, 0x01010004, 0x00010000, 0x00010400, 0x01000004, 0x00000400, 0x00000004, 0x01000404, 0x00010404, 0x01010404, 0x00010004, 0x01010000, 0x01000404, 0x01000004, 0x00000404, 0x00010404, 0x01010400, 0x00000404, 0x01000400, 0x01000400, 0x00000000, 0x00010004, 0x00010400, 0x00000000, 0x01010004};
		
		internal static int[] SP2 = new int[]{unchecked((int) 0x80108020), unchecked((int) 0x80008000), 0x00008000, 0x00108020, 0x00100000, 0x00000020, unchecked((int) 0x80100020), unchecked((int) 0x80008020), unchecked((int) 0x80000020), unchecked((int) 0x80108020), unchecked((int) 0x80108000), unchecked((int) 0x80000000), unchecked((int) 0x80008000), 0x00100000, 0x00000020, unchecked((int) 0x80100020), 0x00108000, 0x00100020, unchecked((int) 0x80008020), 0x00000000, unchecked((int) 0x80000000), 0x00008000, 0x00108020, unchecked((int) 0x80100000), 0x00100020, unchecked((int) 0x80000020), 0x00000000, 0x00108000, 0x00008020, unchecked((int) 0x80108000), unchecked((int) 0x80100000), 0x00008020, 0x00000000, 0x00108020, unchecked((int) 0x80100020), 0x00100000, unchecked((int) 0x80008020), unchecked((int) 0x80100000), unchecked((int) 0x80108000), 0x00008000, unchecked((int) 0x80100000), unchecked((int) 0x80008000), 0x00000020, unchecked((int) 0x80108020), 0x00108020, 0x00000020, 0x00008000, unchecked((int) 0x80000000), 0x00008020, unchecked((int) 0x80108000), 0x00100000, unchecked((int) 0x80000020), 0x00100020, unchecked((int) 0x80008020), unchecked((int) 0x80000020), 0x00100020, 0x00108000, 0x00000000, unchecked((int) 0x80008000), 0x00008020, unchecked((int) 0x80000000), unchecked((int) 0x80100020), unchecked((int) 0x80108020), 0x00108000};
		
		internal static int[] SP3 = new int[]{0x00000208, 0x08020200, 0x00000000, 0x08020008, 0x08000200, 0x00000000, 0x00020208, 0x08000200, 0x00020008, 0x08000008, 0x08000008, 0x00020000, 0x08020208, 0x00020008, 0x08020000, 0x00000208, 0x08000000, 0x00000008, 0x08020200, 0x00000200, 0x00020200, 0x08020000, 0x08020008, 0x00020208, 0x08000208, 0x00020200, 0x00020000, 0x08000208, 0x00000008, 0x08020208, 0x00000200, 0x08000000, 0x08020200, 0x08000000, 0x00020008, 0x00000208, 0x00020000, 0x08020200, 0x08000200, 0x00000000, 0x00000200, 0x00020008, 0x08020208, 0x08000200, 0x08000008, 0x00000200, 0x00000000, 0x08020008, 0x08000208, 0x00020000, 0x08000000, 0x08020208, 0x00000008, 0x00020208, 0x00020200, 0x08000008, 0x08020000, 0x08000208, 0x00000208, 0x08020000, 0x00020208, 0x00000008, 0x08020008, 0x00020200};
		
		internal static int[] SP4 = new int[]{0x00802001, 0x00002081, 0x00002081, 0x00000080, 0x00802080, 0x00800081, 0x00800001, 0x00002001, 0x00000000, 0x00802000, 0x00802000, 0x00802081, 0x00000081, 0x00000000, 0x00800080, 0x00800001, 0x00000001, 0x00002000, 0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002001, 0x00002080, 0x00800081, 0x00000001, 0x00002080, 0x00800080, 0x00002000, 0x00802080, 0x00802081, 0x00000081, 0x00800080, 0x00800001, 0x00802000, 0x00802081, 0x00000081, 0x00000000, 0x00000000, 0x00802000, 0x00002080, 0x00800080, 0x00800081, 0x00000001, 0x00802001, 0x00002081, 0x00002081, 0x00000080, 0x00802081, 0x00000081, 0x00000001, 0x00002000, 0x00800001, 0x00002001, 0x00802080, 0x00800081, 0x00002001, 0x00002080, 0x00800000, 0x00802001, 0x00000080, 0x00800000, 0x00002000, 0x00802080};
		
		internal static int[] SP5 = new int[]{0x00000100, 0x02080100, 0x02080000, 0x42000100, 0x00080000, 0x00000100, 0x40000000, 0x02080000, 0x40080100, 0x00080000, 0x02000100, 0x40080100, 0x42000100, 0x42080000, 0x00080100, 0x40000000, 0x02000000, 0x40080000, 0x40080000, 0x00000000, 0x40000100, 0x42080100, 0x42080100, 0x02000100, 0x42080000, 0x40000100, 0x00000000, 0x42000000, 0x02080100, 0x02000000, 0x42000000, 0x00080100, 0x00080000, 0x42000100, 0x00000100, 0x02000000, 0x40000000, 0x02080000, 0x42000100, 0x40080100, 0x02000100, 0x40000000, 0x42080000, 0x02080100, 0x40080100, 0x00000100, 0x02000000, 0x42080000, 0x42080100, 0x00080100, 0x42000000, 0x42080100, 0x02080000, 0x00000000, 0x40080000, 0x42000000, 0x00080100, 0x02000100, 0x40000100, 0x00080000, 0x00000000, 0x40080000, 0x02080100, 0x40000100};
		
		internal static int[] SP6 = new int[]{0x20000010, 0x20400000, 0x00004000, 0x20404010, 0x20400000, 0x00000010, 0x20404010, 0x00400000, 0x20004000, 0x00404010, 0x00400000, 0x20000010, 0x00400010, 0x20004000, 0x20000000, 0x00004010, 0x00000000, 0x00400010, 0x20004010, 0x00004000, 0x00404000, 0x20004010, 0x00000010, 0x20400010, 0x20400010, 0x00000000, 0x00404010, 0x20404000, 0x00004010, 0x00404000, 0x20404000, 0x20000000, 0x20004000, 0x00000010, 0x20400010, 0x00404000, 0x20404010, 0x00400000, 0x00004010, 0x20000010, 0x00400000, 0x20004000, 0x20000000, 0x00004010, 0x20000010, 0x20404010, 0x00404000, 0x20400000, 0x00404010, 0x20404000, 0x00000000, 0x20400010, 0x00000010, 0x00004000, 0x20400000, 0x00404010, 0x00004000, 0x00400010, 0x20004010, 0x00000000, 0x20404000, 0x20000000, 0x00400010, 0x20004010};
		
		internal static int[] SP7 = new int[]{0x00200000, 0x04200002, 0x04000802, 0x00000000, 0x00000800, 0x04000802, 0x00200802, 0x04200800, 0x04200802, 0x00200000, 0x00000000, 0x04000002, 0x00000002, 0x04000000, 0x04200002, 0x00000802, 0x04000800, 0x00200802, 0x00200002, 0x04000800, 0x04000002, 0x04200000, 0x04200800, 0x00200002, 0x04200000, 0x00000800, 0x00000802, 0x04200802, 0x00200800, 0x00000002, 0x04000000, 0x00200800, 0x04000000, 0x00200800, 0x00200000, 0x04000802, 0x04000802, 0x04200002, 0x04200002, 0x00000002, 0x00200002, 0x04000000, 0x04000800, 0x00200000, 0x04200800, 0x00000802, 0x00200802, 0x04200800, 0x00000802, 0x04000002, 0x04200802, 0x04200000, 0x00200800, 0x00000000, 0x00000002, 0x04200802, 0x00000000, 0x00200802, 0x04200000, 0x00000800, 0x04000002, 0x04000800, 0x00000800, 0x00200002};
		
		internal static int[] SP8 = new int[]{0x10001040, 0x00001000, 0x00040000, 0x10041040, 0x10000000, 0x10001040, 0x00000040, 0x10000000, 0x00040040, 0x10040000, 0x10041040, 0x00041000, 0x10041000, 0x00041040, 0x00001000, 0x00000040, 0x10040000, 0x10000040, 0x10001000, 0x00001040, 0x00041000, 0x00040040, 0x10040040, 0x10041000, 0x00001040, 0x00000000, 0x00000000, 0x10040040, 0x10000040, 0x10001000, 0x00041040, 0x00040000, 0x00041040, 0x00040000, 0x10041000, 0x00001000, 0x00000040, 0x10040040, 0x00001000, 0x00041040, 0x10001000, 0x00000040, 0x10000040, 0x10040000, 0x10040040, 0x10000000, 0x00040000, 0x10001040, 0x00000000, 0x10041040, 0x00040040, 0x10000040, 0x10040000, 0x10001000, 0x10001040, 0x00000000, 0x10041040, 0x00041000, 0x00041000, 0x00001040, 0x00001040, 0x00040040, 0x10000000, 0x10041000};
		
		/// <summary> generate an integer based working key based on our secret key and what we
		/// processing we are planning to do.
		/// 
		/// Acknowledgements for this routine go to James Gillogly & Phil Karn.
		/// (whoever, and wherever they are!).
		/// </summary>
		protected internal virtual int[] generateWorkingKey(bool encrypting, byte[] key, int off)
		{
			int[] newKey = new int[32];
			bool[] pc1m = new bool[56], pcr = new bool[56];
			
			for (int j = 0; j < 56; j++)
			{
				int l = pc1[j];
				
				pc1m[j] = ((key[off + (URShift(l, 3))] & bytebit[l & 7]) != 0);
			}
			
			for (int i = 0; i < 16; i++)
			{
				int l, m, n;
				
				if (encrypting)
				{
					m = i << 1;
				}
				else
				{
					m = (15 - i) << 1;
				}
				
				n = m + 1;
				newKey[m] = newKey[n] = 0;
				
				for (int j = 0; j < 28; j++)
				{
					l = j + totrot[i];
					if (l < 28)
					{
						pcr[j] = pc1m[l];
					}
					else
					{
						pcr[j] = pc1m[l - 28];
					}
				}
				
				for (int j = 28; j < 56; j++)
				{
					l = j + totrot[i];
					if (l < 56)
					{
						pcr[j] = pc1m[l];
					}
					else
					{
						pcr[j] = pc1m[l - 28];
					}
				}
				
				for (int j = 0; j < 24; j++)
				{
					if (pcr[pc2[j]])
					{
						newKey[m] |= bigbyte[j];
					}
					
					if (pcr[pc2[j + 24]])
					{
						newKey[n] |= bigbyte[j];
					}
				}
			}
			
			//
			// store the processed key
			//
			for (int i = 0; i != 32; i += 2)
			{
				int i1, i2;
				
				i1 = newKey[i];
				i2 = newKey[i + 1];
				
				newKey[i] = ((i1 & 0x00fc0000) << 6) | ((i1 & 0x00000fc0) << 10) | (URShift((i2 & 0x00fc0000), 10)) | (URShift((i2 & 0x00000fc0), 6));
				
				newKey[i + 1] = ((i1 & 0x0003f000) << 12) | ((i1 & 0x0000003f) << 16) | (URShift((i2 & 0x0003f000), 4)) | (i2 & 0x0000003f);
			}
			
			return newKey;
		}
		
		/// <summary> the DES engine.</summary>
		protected internal virtual void  desFunc(int[] wKey, byte[] input, int inOff, byte[] output, int outOff)
		{
			int work, right, left;
			
			left = (input[inOff + 0] & 0xff) << 24;
			left |= (input[inOff + 1] & 0xff) << 16;
			left |= (input[inOff + 2] & 0xff) << 8;
			left |= (input[inOff + 3] & 0xff);
			
			right = (input[inOff + 4] & 0xff) << 24;
			right |= (input[inOff + 5] & 0xff) << 16;
			right |= (input[inOff + 6] & 0xff) << 8;
			right |= (input[inOff + 7] & 0xff);
			
			work = ((URShift(left, 4)) ^ right) & 0x0f0f0f0f;
			right ^= work;
			left ^= (work << 4);
			work = ((URShift(left, 16)) ^ right) & 0x0000ffff;
			right ^= work;
			left ^= (work << 16);
			work = ((URShift(right, 2)) ^ left) & 0x33333333;
			left ^= work;
			right ^= (work << 2);
			work = ((URShift(right, 8)) ^ left) & 0x00ff00ff;
			left ^= work;
			right ^= (work << 8);
			right = ((right << 1) | ((URShift(right, 31)) & 1)) & unchecked((int) 0xffffffff);
			work = (left ^ right) & unchecked((int) 0xaaaaaaaa);
			left ^= work;
			right ^= work;
			left = ((left << 1) | ((URShift(left, 31)) & 1)) & unchecked((int) 0xffffffff);
			
			for (int round = 0; round < 8; round++)
			{
				int fval;
				
				work = (right << 28) | (URShift(right, 4));
				work ^= wKey[round * 4 + 0];
				fval = SP7[work & 0x3f];
				fval |= SP5[(URShift(work, 8)) & 0x3f];
				fval |= SP3[(URShift(work, 16)) & 0x3f];
				fval |= SP1[(URShift(work, 24)) & 0x3f];
				work = right ^ wKey[round * 4 + 1];
				fval |= SP8[work & 0x3f];
				fval |= SP6[(URShift(work, 8)) & 0x3f];
				fval |= SP4[(URShift(work, 16)) & 0x3f];
				fval |= SP2[(URShift(work, 24)) & 0x3f];
				left ^= fval;
				work = (left << 28) | (URShift(left, 4));
				work ^= wKey[round * 4 + 2];
				fval = SP7[work & 0x3f];
				fval |= SP5[(URShift(work, 8)) & 0x3f];
				fval |= SP3[(URShift(work, 16)) & 0x3f];
				fval |= SP1[(URShift(work, 24)) & 0x3f];
				work = left ^ wKey[round * 4 + 3];
				fval |= SP8[work & 0x3f];
				fval |= SP6[(URShift(work, 8)) & 0x3f];
				fval |= SP4[(URShift(work, 16)) & 0x3f];
				fval |= SP2[(URShift(work, 24)) & 0x3f];
				right ^= fval;
			}
			
			right = (right << 31) | (URShift(right, 1));
			work = (left ^ right) & unchecked((int) 0xaaaaaaaa);
			left ^= work;
			right ^= work;
			left = (left << 31) | (URShift(left, 1));
			work = ((URShift(left, 8)) ^ right) & 0x00ff00ff;
			right ^= work;
			left ^= (work << 8);
			work = ((URShift(left, 2)) ^ right) & 0x33333333;
			right ^= work;
			left ^= (work << 2);
			work = ((URShift(right, 16)) ^ left) & 0x0000ffff;
			left ^= work;
			right ^= (work << 16);
			work = ((URShift(right, 4)) ^ left) & 0x0f0f0f0f;
			left ^= work;
			right ^= (work << 4);
			
			output[outOff + 0] = (byte) ((URShift(right, 24)) & 0xff);
			output[outOff + 1] = (byte) ((URShift(right, 16)) & 0xff);
			output[outOff + 2] = (byte) ((URShift(right, 8)) & 0xff);
			output[outOff + 3] = (byte) (right & 0xff);
			output[outOff + 4] = (byte) ((URShift(left, 24)) & 0xff);
			output[outOff + 5] = (byte) ((URShift(left, 16)) & 0xff);
			output[outOff + 6] = (byte) ((URShift(left, 8)) & 0xff);
			output[outOff + 7] = (byte) (left & 0xff);
        }

        /// <summary>
        /// Performs an unsigned bitwise right shift with the specified number
        /// </summary>
        /// <param name="number">Number to operate on</param>
        /// <param name="bits">Ammount of bits to shift</param>
        /// <returns>The resulting number from the shift operation</returns>
        public static int URShift(int number, int bits)
        {
            if (number >= 0)
                return number >> bits;
            else
                return (number >> bits) + (2 << ~bits);
        }
	}
}